That system creates osteogenesis in the jaw of a dental patient by surgically cutting a section of the jaw so that the cut section attaches to the coronal member, and as the coronal member separates from the apical member, the jaw segment which has been sectioned slowly moves away from the remaining jaw section so that osteogenesis begins to occur filling the gap between the separated tissue members. The movable segmented jaw section generally moves upwardly to raise the bone and gum level line (for the bottom jaw) to enhance the support structure for a dental implant to be placed in the jaw of the dental patient. By allowing the jaw tissue of the jaw segment (which is movable with respect to the remainder of the jaw) to adhere to the coronal member and move the coronal member vertically, not rotationally, with respect to the distraction member, tissue tear between the movable jaw segment and the coronal member is materially eliminated.
The present invention recognizes that distraction osteogenesis may be generated more simply by merely providing a combination distraction and dental implant system in which the system only comprises a combination dental distraction and implant device which comprises a head and a shaft portion. The shaft, preferably basically cylindrical, comprises a threaded, longitudinal shank section and a smooth-wall distal-end section. The distraction and implant device is engaged in the jaw of the patient in a conventional manner, i.e., by first tapping and screw threading the member into an undercut bore drilled into the jaw. In order to provide distraction osteogenesis, the jaw is surgically cut as described in my prior patent application, and rather than there being separate coronal and apical members, this new invention comprises merely providing a unitary, combination distraction and dental implant device which comprises a head and shaft, with the shaft comprising a threaded, shank section and a smooth, distal wall portion.
After the jaw is surgically cut as described in my prior application and the combined dental implant/distractor of the present invention is inserted in the jaw in the conventional manner, distraction osteogenesis can be generated. This occurs because the smooth, distal end of the device bears against, for instance, a round section in the bone cut surface or a bottom, round jaw surface (an alternate embodiment provides a base support member, like a disc or washer). Thus, further turning of the combined dental implant/distractor cannot cause it to move further in a vertical direction. Rather, as the device is slowly rotated, jaw tissue in the jaw segment (grown toward and adhered to the distraction device) moves upwardly. In order to provide incremental upward movement for the segmented jaw section, the distraction device is rotated and the tissue which adhered to the distraction device separates therefrom. Because of the threaded surface of the upper shank section of the distraction device and the jaw tissue which bears thereagainst, rotation of the device (blocked from vertical movement) will cause the upper segment of the jaw to climb or glide up the inclined plane of the threads or lift upwardly because of the vertical/lifting pressure of the threads against the contiguous and adjoining jaw section segment.
In order to enhance the healing process, in quality and time, between the jaw tissue and the combined distraction/implant device, BMP or other bone growth enhancing material can be introduced. The growth enhancing substance can be applied directly through interior channels in the distraction device either by using a syringe placed downwardly in a throughhole to distribute the BMP radially throughout channels in the device or it may be directly applied to the interstices between the jaw tissue and the distraction device itself. By providing such augmenting tissue restorative material such as BMP, the process for causing distraction osteogenesis and bone healing to occur will be materially enhanced in time while reducing the trauma to the jaw tissue which provides bear ing surfaces for the distraction device.
In another embodiment of this invention, a bottom plate or apical member, preferably a small disc, can be inserted in a drilled bore of the jaw prior to insertion of the combined distraction and implant device so as to provide a more effective bearing surface upon which the smooth distal end of the distraction device will rotate and bear. Such an apical member or thin metal plate could be made of a resorbable material such as PGA or PLA so that placement of the unitary implant and distraction device can be a one-time surgical activity in which the distraction device serves not only to create distraction osteogenesis, but it also serves as the support or implant securing mechanism for a later cap or crown (prosthesis).
The inventor""s own prior, referred-to patent application (reproduced hereinafter) describes a system in which the implant is placed in the lower jaw, upper jaw or is placed in a jaw section (in the latter situation, an H cut is provided so to simultaneously allow the upper and lower jaw segments in a single jaw section to move opposite from each other). Distraction osteogenesis occurs because of their adherence of tissue to the apical and coronal members which move away from each other as the threaded distraction member rotates. In the present invention, separate coronal and apical members are no longer required because the distraction member, itself, is provided with threads in the region in which relative tissue movement is required for the sectioned jaw segmentxe2x80x94whether two segments move opposite to each other, an upper segment moving upwardly towards the sinus or an upper segment in the lower jaw moves to raise the gum line.
The dental implant distraction device of this invention is physically identical, in one embodiment, to FIGS. 8A and 8B of my prior patent application. The device comprises a biocompatible material and is sized to be inserted into the jaw of a patient. Thus, for the patent claims directed solely to the new embodiment of the device itself, FIGS. 8A and 8B of my prior application provide support for the claims and the filing date of the earlier application shall apply to claims reading upon the device depicted in FIGS. 8A and 8B.
This invention is directed to both an apparatus and the method of creating distraction osteogenesis by providing a simple single mechanical unit, a combination dental implant-distraction device which is capable of creating distraction osteogenesis and providing a support for a conventional implant, crown or prosthesis.
The numbering of the Figures in this patent application will commence with FIG. 14 as FIGS. 1 through 13 are taken from my prior patent application which is reproduced in its entirety hereinafter and incorporated expressly herein. For purposes of ease of reference:
FIG. 14 is a perspective view showing the integral, combination dental implant-distraction device of this invention which is also shown in FIGS. 8A and 8B of the prior application;
FIG. 15 is a perspective view similar to FIG. 14 showing a base, disc-like member or flat, apical member upon which the smooth-walled and smooth end, distal portion of the dental implant-distraction device bears during its rotation, thereby providing distraction osteogenesis;
FIGS. 14 and 15 show the position of the dental implant prior to the surgical cut in the bone creating the jaw surgical section segment which moves relative to the remainder of the jaw section; the surgical cuts were described in my prior patent application.
FIG. 16 is an enlarged, partial, sectional view of the threaded portion of the dental implant-distraction device and the jaw tissue growing proximate thereto, which, in combination allows the jaw segment to be moved upwardly as the distraction device incrementally rotates and the threads of the device provide lifting and inclined support for the jaw tissue thereby moving the jaw tissue upwardly when the device is incrementally rotated;
FIG. 17 illustrates another embodiment of this invention in which a covering cap for the dental implant-distractor device is provided for improved hygienics. This embodiment shows a combination dental implant-distraction device with a plurality of internal pathways outwardly or radially emanating from a center bore, extending through the dental implant-distraction device to enhance distribution of BMP, introduced through the top bore, which enhances tissue restoration and bone growth; and
FIG. 18 is an alternative embodiment of this invention in which a center section of the dental implant distraction device is smooth and the longitudinally extended segments are both threaded thereby allowing for concurrent movement of both upper and lower jaw segments with respect to each other by those jaw segments bearing against the upper and lower threaded sections of the dental implant-distraction device. This device could be used to promote, for example, distraction osteogenesis in an upper jaw in two directions, i.e., moving bone growth toward the sinus aarea and moving the gum line to align with adjacent teeth and gum structure.
FIG. 19 is a perspective view of an alternate embodiment of a final connecting member, consistent with the invention fully disclosed in my prior application; and
FIG. 20 is a perspective view of an alternate embodiment of a combination dental implant and distraction member with a coronal member, extra-osseously located.
The following section repeats and corresponds to the specification (written description and drawings FIGS. 1-13, including the Abstract of the Disclosure) of my prior patent application Ser. No. 08/886,078 filed Jul. 2, 1997. To the extent not exactly repeated herein, it is expressly incorporated herein by reference. Minor changes may have been made for clarity and ease of reading.
The present invention relates generally to dental implant systems and methods for replacing missing teeth with dental implants, more particularly, to dental implant systems and surgical methods for replacing teeth with dental implants in areas of the mouth that have suffered bone loss and most particularly to combination distraction dental implant devices and methods for replacing missing teeth in areas of the jaw bone having bone loss using a three component combination distraction dental implant device including two cylindrical like components and a connecting third component or an expansion third component to grow new bone and soft tissue by distraction osteogenesis;
Premature tooth loss can limit a patient""s ability to chew and speak clearly. Consequently, patients request tooth replacement. In the past, dentists have been able to replace missing teeth by means of removable prosthesis such as partial or complete dentures. Other prior alternatives included the placement of fixed bridge work cemented to adjacent teeth. These two prior methods served only to fill the void of the edentulous space by replacing the crown of the involved teeth but did not replace the root.
Recently, the field of dental implantology has come into its own, as the technology for replacement of the root and the crown portion of the missing teeth has evolved. In dental implantology, the root portion of the missing tooth is replaced first, by surgically implanting a cylindrical root form dental implant into the dentoalveolar bone (Stage I). There are a number of U.S. Patents relating to dental implants, including the following: U.S. Pat. Nos. 5,489,210; 5,470,230; 5,449,291; 5,334,024; 5,281,140; 5,269,685; 5,259,759; 5,154,612; 5,145,371; 5,125,841; 5,069,622; 5,064,425; 5,051,880; 4,960,381; 4,824,372; 4,798,205; 4,682,951; 4,657,510; 4,552,532 and 4,330,891 the disclosure of each is herein incorporated by reference.
As the surgical site heals, the dental implant becomes bonded and incorporated into the surrounding bone forming an integral unit. The dental implant abutment for the creation of the crown of the tooth later, once osseous healing had occurred (4-6 months), is placed at the time of Stage II uncovering.
In some instances, the above is accomplished by a one-stage implant procedure. In the one-stage procedure, also known as the nonsubmerged, either a one-piece fixture, in which the implant and transmucosal portion are fused together, or both an implant body and a healing cap are simultaneously placed. Instead of covering the implant, the soft tissue is sutured around the protruding transmucosal portion or healing cap and left to heal for the same 4 to 6 months. The advantages of one-stage implants is described in detail in an article by Louis F. Clarizio, DDS, entitled xe2x80x9cOne-stage Implants: An Overview of Their Usefulness and the Techniques for Placementxe2x80x9d in the Postgraduate Dentistry Series, Volume 3, Number 4, 1996 beginning at page 3, the disclosure of which is hereby incorporated by reference.
Regardless of whether a one-stage or a two-stage implant is used, long term success of dental implants depends upon two factors: (1) the osseous incorporation or integration of the implant with the native bone, and (2) the mechanical loading properties of the prosthetic crown onto the dental implant. Ideally, the longest (13-15 mm) and widest (2.5xe2x88x925.5 mm) dental implant should be placed in the bone to act as a proper foundation for the tooth crown.
However, as a consequence of premature tooth loss, patients have lost bone in the area of a proposed implant. This bone loss has, in some cases, limited the surgical options, requiring the dentist to place a smaller than optimal sized dental implant. If the dental implant is too small to accommodate the mechanical load from chewing, with time, it will loosen and fail. Thus, the longest and widest implant available, as described above, (based on the bone stock) should be placed. Additionally, due to bone loss or insufficient bone in the implant area, the dental implant may be placed in an anatomical location where the existing bone may not be ideal for prosthetic reconstruction with a crown or bridge, forcing the dentist to replace the missing tooth with a crown that is not as aesthetic or functional as would be considered optimal.
One prior solution to this bone loss problem was to augment the bony bed with the patient""s own bone or cadaveric bone as a transplant, or with synthetic bone substitutes. This procedure was done at the time of dental implant placement if the bone loss is not too great. Otherwise the bone augmentation must be done as a first surgical procedure with the placement of the dental implant occurring several months later, as a second surgical procedure, once healing of the bone graft was completed.
Due to the anatomy of the craniofacial region (defined as pertaining to the region of the head which contains the craniofacial bones, including the maxilla, the upper jaw bone includes the bones of the eyes, the hard palate and the nose, and the mandible, the lower jaw bone, usually with reference to specialized surgical or prosthetic reconstructions of this area of the face), augmentation of the deficient bone is not as simple as layering on the transplanted bone and allowing it to heal. Occasionally, the maxillary sinus membrane (located in the upper jaw) must be elevated or the inferior alveolar nerve (located in the lower jaw) transposed to allow room for placement of the bone graft. Regardless of the technique and materials used, the potential morbidity to the patient can be significant.
Another prior technique of producing new bone was that of distraction osteogenesis. Here, the body was xe2x80x9ctrickedxe2x80x9d into making new bone as it attempts to heal a fracture site. Using this technique, the surgeon created an osteotomy or cut in the bone in an area of bone deficiency. As long as a non-critical size gap exists, the body attempts to heal itself by filling in the gap with new bone. If the gap is widened daily, the body recognizes the newly expanded gap and continues to fill the gap with new bone. This results in creation of new bone in the expansion gap. As long as the gap is expanded slowly over time (0.5-2.0 millimeters per day), the body continues to heal the gap, generating new bone.
A critical size defect is one that will not heal on its own i.e. a critical size defect is sufficiently large to allow only for connective tissue healing without bone bridging between the two ends of the defect. A non critical defect is one which will heal on its own by filling in with bone. Each bone of the body has its own xe2x80x9ccritical sizexe2x80x9d defect. If a critical size-defect exists, then a bone graft or a bone substitute must be placed to allow for osseous regeneration.
Since the native bone is utilized as the template for repair, the new bone generated has the same size and shape as the original bone. This phenomenon of recreating the same size and shape as the original bone is unique to bone generation using distraction osteogenesis and is not accomplished with conventional bone transplantation.
During distraction osteogenesis, in addition to creating new bone, the overlying soft tissues are regenerated, a secondary gain unique to distraction osteogenesis. This secondary beneficial effect has significant clinical implications, for not only is the underlying foundation properly established, but also the overlying soft tissue is recreated providing for aesthetic and functional rehabilitation of the defect.
Distraction osteogenesis defined as the generation of new bone in response to the application of tension stresses placed across an osteotomy site (bone cut site), has been successfully applied to the bones of the maxillofacial region and specifically to the dentoalveolar unit using distraction devices that are external to at least the gums inside the mouth and, in some cases, completely external the mouth. In these prior instances of applying distraction osteogenesis prior to placing a dental implant, an osteotomy (corticotomy) is made in the bone adjacent to the area requiring bone augmentation and one of the prior bone expansion devices was applied. After allowing for a period of initial healing, the prior device was activated by the patient at home, advancing the distraction gap about 0.5 to about 2.0 millimeters a day. For a more complete description of distraction osteogenesis, see the article xe2x80x9cOsteodistractionxe2x80x9d by the inventor of the present application in Selected Readings in Oral and Maxillofacial Surgery, volume 4, Number 7, published by the University of Texas, Southwestern Medical Center at Dallas, in 1996, the disclosure of which is herein incorporated by reference.
After a sufficient amount of new bone matrix was generated, the distraction device was left in place to allow for ossification of the newly generated bone. The prior distraction devices were then removed during a second surgical procedure and dental implant(s) are placed. Once again the patient was required to undergo two surgical procedures: (1) bone generation via distraction osteogenesis and (2) placement of the dental implant.
A minimum of about ten (10) to about fifteen (15) millimeters of bone was required to utilize the existing distraction devices. If there was not enough bone stock to place the existing devices, a bone graft was required prior to the distraction device being placed. In this case, the patient was required to undergo three separate surgical procedures.
The current external and submerged distraction devices are also limited in the amount of bone expansion each device can deliver because they have fixed internal mechanisms which provide for bone expansion from 0.0 mm to the full length specified for a particular device. Presently, for an external distraction device the full length is about 40 mm while for an intraoral distraction device, the full length is about 18 to about 20 mm. Should more bone expansion be required, then a new device was required to be placed during yet another surgical procedure (fourth).
These prior distraction devices took essentially two approaches: (1) the device was situated externally, outside the skin, with pins holding the device in place to the bone, or (2) the device was situated intraorally, inside the mouth, along the gum line, with pins or screws holding the device in place. Devices which are located externally function well but can pose aesthetic concerns while the patient is utilizing the device and also facial scars are created as the pins holding the device in place are moved as the device is activated and the bone is expanded. Intraoral devices do not have as many aesthetic concerns, but are bulky, displacing the lips and cheeks, which can give the patient the appearance of a local infection.
As can be seen above, in the worst case, some patients were required to undergo as many as four (4) separate surgical procedures over a lengthy time period in order to achieve an optimal dental implant. It should be obvious that it is desirable to limit the number of surgical procedure a patient must undergo.
Thus, there is a need for new devices and methods for placing optimally sized dental implants in areas having insufficient bone. Such new devices and methods should reduce the number of surgical procedures a patient must undergo to achieve an optimal implant; should significantly reduce the number of individual distraction devices required for obtaining the appropriate amount of bone in the implant site; should reduce the number of surgical procedures required for placing an optimal implant in the implant site; should incorporate as many features of the prior devices as possible into a combination distraction dental implant device; should reduce patients aesthetic concerns; should reduce, if not totally eliminate, displaced lips and cheeks and should reduce, if not totally eliminate, the need for bone grafts.
It is accordingly one object of the present application to provide a new combination dental implant and distraction device and method of using which limits the number of surgical procedures a patient must undergo to have an optimum dental implant placed in an area having initially insufficient bone stock.
Another object of the present invention is to provide a combination distraction dental implant device and method of using the device that combines the technology of dental implantology and that of distraction osteogenesis such that a combination distraction dental implant can be utilized as both the bone distraction device and, after the distraction, left in place as the dental implant.
A still further object of the invention is to provide a combination distraction dental implant device that is utilized as the root form for a prosthesis such as, for example, a crown, a bridge or dentures.
Another object of the invention is to provide a combination distraction dental implant that eliminates the need for the complete removal of the distraction device prior to placement of a separate dental implant during another surgical procedure.
A further object of the present invention is to provide a combination distraction dental implant that eliminates the need for bone grafts in areas of limited bone stock in order to place optimal dental implants.
Another object of the invention is to provide a combination distraction dental implant that lifts the sinus during the distraction process.
The above and other objects of the present invention are realized by combining the technology of dental implantology and that of distraction osteogenesis to produce a combination distraction dental implant which serves as both the implant and the distraction device. In preferred embodiments and methods of the present invention, a combination distraction dental implant is utilized as both the distraction or bone expansion device and the dental implant device and is left in place after distraction in the place of the prior conventional dental implant.
One representative embodiment of a specific combination distraction dental implant comprises: a hollow coronal component; a partially hollow apical component initially having at least one surface contiguous with at least one surface of the hollow coronal component; and at least one expansion component for: (a) operatively connecting the hollow coronal component and the partially hollow apical component, and (b) controllably expanding the distance between the contiguous surfaces of the hollow coronal component and the partially hollow apical component to form a gap.
Another representative embodiment of a specific combination distraction dental implant for placing an optimum dental implant in an area having initially insufficient bone stock comprises: a hollow coronal component; a partially hollow apical component operatively positioned proximal the hollow coronal component; and a removable connecting component operatively connecting the hollow coronal component and the partially hollow apical component.
One representative method of the present invention includes the steps of: providing a three component distraction device including a hollow coronal component, a partially hollow apical component and a linking component or a first expansion component; placing the combination distraction device in a predetermined site where bone regeneration is required; allowing the combination distraction device to become integrated into the bone; ensuring that osseous incorporation of the combination distraction device into the bone has been accomplished; performing a corticotomy in the buccal bone at the level of the contiguous surfaces of two of the three components of the combination distraction device to form a distraction gap; educating the patient as to the care and activation of the three component combination distraction device; after allowing for a period of initial healing, maneuvering the connecting component thereby separating the coronal component and the apical component to widen the distraction gap in the bone.
Another representative embodiment of a more general purpose distraction device of the present invention includes: a first component selectively operatively removably connectable to a first predetermined portion of a bone; a second component selectively operatively removably connectable to a second predetermined portion of the bone, the second component being operatively positioned proximal the first component; and a connecting component for: (a) operatively connecting the first and the second components, and (b) controllably expanding the distance between the first and the second components.
Other objects and advantages of the present application will become apparent from the following description, the accompanying drawings and the appended claims.